Ammonium hexafluorosilicate salts

Hexafluorosilicates of bis(carboxypyridinium) and bis(2-carboxyquinolinium)

“…Such a slightly distorted octahedral geometry is typical for [SiF 6 ] 2À anion involved in the system of hydrogen bonding. The relationship between Si-F bond length and hydrogen bonding is also observed in bis(piperidinium) hexafluorosilicate, bis(quinolinium) hexafluorosilicate monohydrate, and in N-methylpiperidine betaine hexafluorosilicate [11,12] and surprisingly is not observed in bis(methylammonium) hexafluorosilicate [11]. The 4-carboxypyridinium cation in III has a practically planar skeleton with the twisted angle between the pyridinium ring and the carboxylic group equal to 23.78.…”

Synthesis and structure of fluorosilicic acid compounds with 4-aminobenzoic acid and with 4-aminobenzenesulfonamide

“…The linear and aromatic amines, alkylamines [9,14], propargilamine [15], nitrogen-containing heterocycles of piperidine or quinoline types [9], the derivatives of guanine [16,17], hydrazides, thiosemicarbazides, protonated by the FSA, form co-crystals exclusively with highly symmetric hexafluorosilicate anion, [SiF 6 ] 2À . The most interesting products with diversified structures were formed in the reactions of FSA with crown ethers and their partially substituted aza analogs.…”

“…Thus, in bis(N,N 0 -bis(3-nitrophenyl)isophthalamide) tetra-n-butylammonium hexafluorosilicate [7], each [SiF 6 ] 2À anion is connected via its equatorial fluorine atoms within the crown-like cavity formed by two N,N 0 -bis(3-nitrophenyl)isophthalamide residues. In cocrystals with acridinium [8] and quinolinium [9] cations, only two or five over six fluorine atoms participate in hydrogen bond network. Hydrates of p-bromoanilinium and p-toluidinium hexafluorosilicates [10] both formulate a thick layer with two hydrophobic surfaces formed by the aromatic rings arranged perpendicular to the layer surface and the hexagonal H-bonded network inside the layer.…”

The variations in hydrogen bonding in hexafluorosilicate salts of protonated methyl substituted pyridines and tetramethylethylenediamine

“…The electrostatic attractive forces between these cations and the anions [SiF 6 ] 2À facilitates the formation of extensive N-HÁ Á ÁF hydrogen-bond interactions [4][5][6][7][8][9][10][11][12][13][14]. The hydrogen bonds between ions are much stronger than between molecules and can play dominant roles in crystal structures [15].…”

“…The hydrogen bonds between ions are much stronger than between molecules and can play dominant roles in crystal structures [15]. This hydrogen-bonding network is prone to incorporate during the crystallization the water molecules which participate in hydrogen bonding [4,9,[12][13][14].…”